The invention relates to a luminaire comprising:
a base wall with a first contact element and a second contact element electrically insulated from the first; PA1 an electric lamp with a tubular lamp vessel having a first and a second end portion, in which lamp vessel an electric element is accommodated and connected to current conductors which issue from the lamp vessel to the exterior at respective end portions; PA1 wherein each contact element is bent from metal strip material so as to have a base and a first and an opposing second arm extending away from the base and having a longitudinal direction, which arms have a first and a second contact portion, respectively, at a distance from the base and facing one another, thus keeping one of the current conductors of the lamp clamped in between them.
Such a luminaire is known from U.S. Pat. No. 3,267,275.
The contact elements of the known luminaire are substantially U-shaped. Their arms extend away from the base opposite to one another.
If a current conductor is to be gripped with clamping force, the arms must be closer together with their contact portions in the idle position, when there is no lamp, than in their operational position, when a lamp is present. To keep the lamp clamped in between them, the arms must first move apart comparatively far during taking-up of the lamp in order to allow the current conductor access to the contact portions, and then spring back into the operational position. It is important that the arms are not plastically deformed when the lamp is inserted, because this would mean the clamping force in the operational position is lost.
Plastic deformation can be prevented by giving contact elements comparatively long arms. Only a small elastic deformation need occur per unit length of the arms in order to allow the free-end portions to move apart comparatively far. A disadvantage of this is, however, that the constructional height of the contact elements, i.e. the distance from their free-end portions to the base, becomes comparatively great. Plastic deformation can also be prevented by the choice of a material which has a strong elastic deformability. Such material has the disadvantage, however, that the clamping force of the contact element formed therefrom is small.